The heating is lost in my ECC 1992 V8,
after visiting a shopping mall I thought the car was quite warm so I selected temperature "LO" on the ECC. Shouldn´t have done that, now it is stuck as it seems.

According to the service manual an ECC fault code I have is C1, "Heizungsventil geschlossen".

Can anyone please tell if this "Heizungsventil" controls the airflow or the coolant fluid? Where is it located?

Thanks!

Thomas